Virtual image displays combine magnifying optics with a small image panel to provide the viewer with a virtual image capable of displaying large amounts of information. Such displays have found application in so called head mounted displays and are used in conjunction with a computer-based device for a variety of applications. As is known, the computer-based device includes processing and display driver circuitry for generating the image signal to be displayed via the optics and image panel.
However, such conventional virtual image displays are known to have many shortcomings. For example, such displays have suffered from being too heavy for comfortable use, as well as too large so as to be obtrusive, distracting, and even disorienting. These defects stem from, among other things, the incorporation of relatively large optics systems within the mounting structures, as well as physical designs which fail to adequately take into account such important human factors as size, shape, weight, etc.
Examples of some conventional head mounted virtual displays are shown in FIGS. 1 and 2. FIG. 1 illustrates a head mounted virtual display unit 10 which rests on the users head and face in a manner similar to that of a pair of eye glasses. The user views virtual images through the display portion 12. Nose bridge 14 and side supports 16 serve to provide support for the display while on the users head and face. The unit 10 may be connected to a computer via connector 18. It is known that such a unit is cumbersome and permits the wearer to see substantially nothing other than the display screen. That is, the user is unable to view his immediate environment. Such a head mounted virtual display is disclosed in an international patent application identified as WO 95/11473, the disclosure of which is incorporated herein by reference.
FIG. 2 illustrates a head mounted monocular virtual display unit 20. The support structure 12 is positioned on a users head and the display portion 14 comes down in the users field of vision. This design is also known to be cumbersome and likely to obstruct the users surrounding view. Such a head mounted monocular virtual display is also disclosed in a the international patent application identified as WO 95/11473.
Other examples of conventional compact display systems and head mounted displays are disclosed in U.S. Pat. No. 5,771,124 to Kintz et al., U.S. Pat. No. 5,757,339 to Williams et al., and U.S. Pat. No. 5,844,656 to Ronzani et al., the disclosures of which are incorporated herein by reference. Still further, it is known that Sony Corporation makes a head mounted virtual display known as the "Glasstron."
However, all of the examples given suffer from one or more of the above-mentioned design deficiencies. As a result, such deficiencies have seriously hindered the general acceptance of such devices.
Accordingly, there is a need for a compact optical system for use in display devices, for example, personal devices such as wearable personal computers, head mounted displays, portable telephones and the like, which substantially reduces or eliminates these and other deficiencies.